This is Why

Study Shows Link Between Suicidal Behavior in Parents and Children

In a study published in JAMA Psychiatry, researchers noted that previous studies have already pointed out the possibility that suicide risk runs in the family, with young people likelier to attempt suicide in a period of two years after a parent's suicidal attempt. However, David Brent, M.D. from the University of Pittsburgh Medical Center and colleagues wanted instead to explore what exactly causes suicidal behavior to run in a family.
Researchers were also able to spot an increase in the incidence of depression in the children as the study progressed, growing from 29.6 percent in the first two years to 48.2 percent at the end. This increase in depression might also be the reason for the increased number of attempted suicides by children with suicidal parents.
Interventions targeting impulsive aggression are recommended to reduce risks of suicide attempts in children from high-risk families, the researchers added.

Excuse me...
If your results are occurring within two years, that is not accounted for by genetics.   Maybe some kind of lifetime risk is, but not these short term effects.

Epidemiology 101 says...  this is the result of contact with an infection that has a rather long latency period.  ( I don't know, something like periodontitis maybe?)

If they climbed to the roof and their heads exploded, you might have considered something like that I guess...  but no-  this behavior is clearly voluntary, right?

Low level infection would also account for the initial depressive symptoms.

Your data is fully consistent with an infection progressing to sepsis and causing delirium.
In both the parent and the child.
There is probably a genetic component to their immune response, but if you looked a little further you would notice the same thing happens among couples.
These results are clearly triggered and exacerbated by living arrangements.

This is not a mystery.   This is is easily explained by simple, well documented processes.  And your lack of familiarity with basic medical concepts and distribution analysis is what has fueled this tragic cycle for the last century. 

I'm pretty sure "interventions targeting impulsive aggression" is another euphemism for "chemical restraints", so yeah, go fck your high-risk self.